Arguable and its adverbial sibling, arguably, tremble like the needle of a Scout compass between referring to that for which a case can be made, on one hand, and then to that which isn't settled yet but is rather "open to dispute," on the other.

And of course any given assertion can be in both states at once. That's the nature of argument, isn't it? By definition, a point can be argued from either side.

To say something is arguable isn't always quite the same as arguing for it. "A case could be made for that, but I'm not going to make it."

Conversely, things get to be "inarguable" because they're completely settled: "I was so pleased to hear that Joe got the chief of staff position. He is inarguably well qualified for it." You can't argue against it, and you needn't argue for it, because it's settled.

The mental image that helps me deal with all this is what I think of as "the ladder of certainty."

If, for instance, I want to go out on a limb over a current literary favorite, I might say, "Buster Jones is arguably the finest poet of his generation."

I'm staking a claim; remember, even if you count "arguably" as a weasel word, the bones of the sentence are still "Jones is the finest poet." But with "arguably," I'm acknowledging that others may differ, may not even think of poor Buster as a serious homme de lettres at all.

When I say this, I'm climbing up a rung on the ladder of certainty. I've started from a low base. ("Buster who?" my interlocutors may ask.) But the direction is up.

Suppose, on the other hand, I happen to have tea with V.S. Naipaul. As you may know, he recently established himself as a leading literary misogynist by disrespecting women writers generally in a June interview with the Royal Geographical Society. Should I mention Jane Austen, and how it is a truth universally acknowledged that she's one of the great writers in English, he may respond along the lines of, "Hmph. That's arguable."

In this case, I've started fairly high up on the ladder of certainty ("a truth universally acknowledged") and Mr. Naipaul is taking me down a rung.

Barbara Wallraff, longtime language maven at The Atlantic and general defender of common sense, had this to say about arguably a few years ago: "When people say that something is 'arguably' a good idea, they mean they'd be willing to argue in favor of it. But if they say something is "only arguably" a good idea, that means they'd argue against it. This may seem like awfully unruly behavior on the part of a word, but 'arguably' is not alone in acting this way."

At this point I've been looking at arguably long enough that, especially in the all-caps style favored by some of the dictionaries I've been checking, the word appears to be ar-GWOB-bly, which I can imagine as some kind of Latin American fruit to be found in the Truly Exotic Department at Whole Foods. Enough for now. More next week.